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Theoretical Investigations of Weakly Bound Complexes: Spectroscopy and Dynamics

Ray, Sara E.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1269382390

Abstract Details

2010, Doctor of Philosophy, Ohio State University, Chemistry.
The spectroscopy and dynamics of various van der Waals complexes have been in- vesitgated. The electronic spectra resulting from the (B-X) transitions in He-Br2 and He-I2 were calculated and compared to each other and to experiment. Differences in the higher energy spectral feature in both the experimental and calculated spectra led to the question of the origin of its structure. To investigate this difference, the He-Br2 spectrum using the parameters from the He-I2 B-state potential surface, and the He-I2 spectrum using the B-state potential parameters of He-Br2 were calculated. It was determined that the features within the spectra are dictated by the rotational structure of the I2/Br2 rather than the anisotropies in the potential surface. This theory was further tested by approximating the He-I2 B-state surface as a simplified elliptical potential which further demonstrated that the spectral structure of these systems, initially believed to be very complex, can be described with simple models that are relatively insensitive to the details of the potential surface. Excited-state probability amplitudes and their corresponding energies have been calculated for the H2-I2 and D2-I2 systems to gain insights into the nature of the excited states. Due to the nature of the van der Waals bond between the H2/D2 and the I2 and the relative insensitivity of these rare gas-dihalogen complexes to the details of the excited-state surfaces, it was assumed that there is little dependence on the orientation of the H2/D2 axis relative to the I2, and the H2/D2 were treated as spherical. The calculations of the H2-I2 and D2-I2 intermolecular vibrational energies within the H2/D2 + I2(B,v'=20) potential energy surface (PES), using a scaled potential model based on the He + I2(B,v'=20) were performed, and the resulting energies were compared to experiment to help in the assignment of spectral features. To investigate the dynamics of van der Waals species, hydrogen-transfer reactions were probed through vibrational excitation of the HCl bond in the pre-reactive F-HCl complex. A three-dimensional, fully-coupled potential energy surface has been constructed based on electronic energies calculated at the multireference configuration interaction+Davidson correction (MRCI+Q) level of theory with an aug-cc-pVnZ (n=2,3,4) basis. Here the results of time-dependent quantum wave packet calculations where the reaction is initiated by vibrationally exciting the HCl stretching motion in the pre-reactive F-HCl complex are presented. Product state distributions are calculated for reactions initiated in the first three vibrationally excited states of HCl, and results show that we see a promotion of the reaction for all three excitations with the probability of reaction increasing with increasing energy.
Anne McCoy, PhD (Advisor)
Terry Miller, PhD (Committee Member)
Russell Pitzer, PhD (Committee Member)
Scott Sheer, PhD (Committee Member)
130 p.
Chemistry
theoretical chemistry; van der Waals; rare gas; dynamics; spectroscopy

Recommended Citations

Citations

  • Ray, S. E. (2010). Theoretical Investigations of Weakly Bound Complexes: Spectroscopy and Dynamics [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1269382390

    APA Style (7th edition)

  • Ray, Sara. Theoretical Investigations of Weakly Bound Complexes: Spectroscopy and Dynamics. 2010. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1269382390.

    MLA Style (8th edition)

  • Ray, Sara. "Theoretical Investigations of Weakly Bound Complexes: Spectroscopy and Dynamics." Doctoral dissertation, Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1269382390

    Chicago Manual of Style (17th edition)

osu1269382390
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This open access ETD is published by The Ohio State University and OhioLINK.